questions regarding "Inactive", "Cache" and "Buffers" memory

[Martin T]

Hi,

FreeBSD "top" utility categorizes memory into "Active", "Inact",
"Wired", "Cache", "Buf" and "Free" sections. For example:

Mem: 125M Active, 42M Inact, 51M Wired, 17M Cache, 34M Buf, 2720K Free
Swap: 512M Total, 512M Free


Those sections should have following meanings:

Active: Memory currently being used by processes.
Inactive: Memory that was used by processes that are no longer
running, but is cached since it may be used again.
Wired: Memory in use by the FreeBSD kernel. This memory cannot be swapped out.
Cache: Memory being used to cache data. Can be freed immediately if required.
Buffers: Disk(HDD/SSD) cache.
Free: Completely free and ready to use.


Questions:

1) Is it possible to flush "Inactive", "Cache" or "Buffers" memory? Or
can this be done only be kernel automatically?

2) What is the difference between "Cache" and "Buffers" memory?



thanks,
Martin